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Resumen El transporte de albumina en el intestino delgado del cerdo esta asociado con un aumento en el transporte de fluido. Ambos transportes son inhibidos por altas concentraciones de calcio. Ausencia de calcio tambien inhibe el transporte de albumina. Condiciones optimas en el transporte de albumina y fluido se obtienen usando Cl2Ca4 mM en el medio. Se deducen analogias al comparar estos resultados con resultados similares en ameba, obtenidos de la literatura. 相似文献
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Evershed RP Payne S Sherratt AG Copley MS Coolidge J Urem-Kotsu D Kotsakis K Ozdoğan M Ozdoğan AE Nieuwenhuyse O Akkermans PM Bailey D Andeescu RR Campbell S Farid S Hodder I Yalman N Ozbaşaran M Biçakci E Garfinkel Y Levy T Burton MM 《Nature》2008,455(7212):528-531
The domestication of cattle, sheep and goats had already taken place in the Near East by the eighth millennium bc. Although there would have been considerable economic and nutritional gains from using these animals for their milk and other products from living animals-that is, traction and wool-the first clear evidence for these appears much later, from the late fifth and fourth millennia bc. Hence, the timing and region in which milking was first practised remain unknown. Organic residues preserved in archaeological pottery have provided direct evidence for the use of milk in the fourth millennium in Britain, and in the sixth millennium in eastern Europe, based on the delta(13)C values of the major fatty acids of milk fat. Here we apply this approach to more than 2,200 pottery vessels from sites in the Near East and southeastern Europe dating from the fifth to the seventh millennia bc. We show that milk was in use by the seventh millennium; this is the earliest direct evidence to date. Milking was particularly important in northwestern Anatolia, pointing to regional differences linked with conditions more favourable to cattle compared to other regions, where sheep and goats were relatively common and milk use less important. The latter is supported by correlations between the fat type and animal bone evidence. 相似文献
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Structure of the Ebola virus glycoprotein bound to an antibody from a human survivor 总被引:1,自引:0,他引:1
Ebola virus (EBOV) entry requires the surface glycoprotein (GP) to initiate attachment and fusion of viral and host membranes. Here we report the crystal structure of EBOV GP in its trimeric, pre-fusion conformation (GP1+GP2) bound to a neutralizing antibody, KZ52, derived from a human survivor of the 1995 Kikwit outbreak. Three GP1 viral attachment subunits assemble to form a chalice, cradled by the GP2 fusion subunits, while a novel glycan cap and projected mucin-like domain restrict access to the conserved receptor-binding site sequestered in the chalice bowl. The glycocalyx surrounding GP is likely central to immune evasion and may explain why survivors have insignificant neutralizing antibody titres. KZ52 recognizes a protein epitope at the chalice base where it clamps several regions of the pre-fusion GP2 to the amino terminus of GP1. This structure provides a template for unravelling the mechanism of EBOV GP-mediated fusion and for future immunotherapeutic development. 相似文献
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Hanging gardens and wet wall habitats have been studied for the past several years in many arid regions of the Intermountain West. One unusual large wet wall habitat in Zion National Park was found to be covered with a mucilaginous red-colored growth of the filamentous gliding bacterium Thioploca ingrica Visloukh. This is the only habitat we have examined where the predominant matrix-forming organism was a bacterium rather than an alga. 相似文献
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Burton Voorhees 《Foundations of Science》2002,7(1-2):213-227